磷酸银复合微系统的可控构筑及其光解水制氢性能研究

Photocatalytic decomposition of water to hydrogen is an important way to solve the energy shortage problem. Current catalysts for photocatalytic decomposition of water have such disadvantage as low efficiency and failure to use visible light efficiently. Silver phosphate can utilize up to 90% of visible light to produce quantus. This project is aimed to bond titanium dioxide nanomaterials on the surface of silver phosphate crystals with excellent photocatalytic performance. Under the sunlight, silver phosphate can absorb visible light with wavelength less than 530 nm and induce valence band electrons to transit to the valence band of TiO2. The valence electrons of TiO2 are then excitated to transit to conduction band of itself.,and reduce the water molecules to hydrogen. Well-organized silver phosphate crystals with a high specific surface area and porous structure is obtained though construsting a liquid film transmission system and controlled under Small organic molecules. titanium dioxide nanomaterials is bonded on the surface of silver phosphate crystals utilizing molecular bond technology to construct a series of microsystems for photocatalytic decomposition of water. Such factors as crystal growth orientation, crystal defect, surface active position, acting force between assembly units are separately researched, according to first principle to discuss the inherent relevance between microsystems structure and their photocatalytic performance. Mathematical model is used to illustrate the mechanism for microsystems to enhance the photocatalysis ability. This can provide some theoretical basis for photo splitting of water to hydrogen.

利用太阳光催化分解水制取氢气，是解决人类能源问题的重要途径。目前光解水制氢用催化剂存在制氢效率低、不能直接高效利用可见光等不足。磷酸银利用太阳光的可见光区量子产率高达90%，本项目拟利用磷酸银优异的光催化性能，在其晶体表面键合二氧化钛，磷酸银在太阳光照射下吸收波长小于530 nm可见光波，其价带电子被激发跃迁至二氧化钛的价带，二氧化钛的价电子再被激发并跃迁至自身导带，将表面的水分子还原产生氢气；建立液膜传输系统结合有机小分子的调控作用，获得规则有序的大比表面积磷酸银有序多孔结构，并在其表面利用分子键合技术复合二氧化钛，形成结构紧密、制氢高效的微系统；将晶体生长取向、晶面缺陷、表面活性位、键合作用力等因素有效分离，结合第一性原理计算结果探讨磷酸银微系统的结构与性能的相关性问题；拟合数学模型，阐明磷酸银微系统能够提高催化制氢效率的作用机制，为磷酸银复合微系统利用太阳光高效解水制氢提供理论支持。

本项目从控制催化材料的表面形貌、晶体结构、比表面积及化学组成等角度着手，设计合成出了一系列性能优异的可见光催化材料。我们首次提出动态模板法，即在催化材料生成过程中，晶体表面光生电子促进高分子单体的聚合，而单体聚合产生的能量又反作用于晶体并对其生长进行微扰，使其具有大比表面积和多孔状结构，结构类似于化工微反应器单元，从而大大提高了磷酸银基催化材料的光降解效率；利用光控合成技术，获得了磷酸银纳米晶簇，并设计成可连续降解的反应器，实现了污水的高效快速降解；通过原位键合技术，将磷酸银和二氧化钛有效复合，异质结构提高了光降解效率，为光解水制氢奠定了良好的材料基础。研究还发现，控制晶体表面缺陷及对材料进行掺杂和修饰，是提高光催化活性的有效途径，用于指导氧化锌基催化剂的结构调控及掺杂改性，取得的效果也非常理想。该项目已发表SCI论文13篇，申请国家发明专利4项，研究结论对于可见光催化材料的工业化生产及实际应用极具参考价值。目前已授权的磷酸银纳米晶簇光控合成技术和掺铝氧化锌光电材料制备技术这两项专利已成功实现向应用企业的转让。